warning cleanup.

- fix mistake with grease pencil UI (&& was intended but & used).
- use (void) rather then () across _all_ blenders code.
- a few minor edits, don't shadow stack variables in roll calculation & avoid running memset() for VBO vertex map.

source/blender/blenkernel/intern/suggestions.c

@@ -88,7 +88,7 @@ void texttool_text_set_active(Text *text) {
 	activeToolText = text;
 }
 
-void texttool_text_clear() {
+void texttool_text_clear(void) {
 	free_texttools();
 	activeToolText = NULL;
 }